Utilization of steam-exploded corn straw to produce biofuel butanol via fermentation with a newly selected strain of Clostridium acetobutylicum

Abstract

The feasibility of utilizing corn straws to produce butanol via fermentation with Clostridium acetobutylicum was evaluated. The supernatant of enzymatically hydrolyzed supernatant of steam-exploded corn straws was used as the raw material. A bacterial strain was selected from Clostridium acetobutylicum zzu-02 and Clostridium beijerinckii zzu-01, which was capable of fermenting the enzymatically hydrolyzed supernatant of steam-exploded corn straw to produce butanol with high yield. The optimal fermentation conditions for the selected strain with enzymatically hydrolyzed supernatant of steam-exploded corn straw were also investigated and they were determined as follows: sugar concentrations in enzymatically hydrolyzed solution of steam exploded corn straws, 57.5 g/L; initial pH, 6.3; the amount of added CaCO3, 5g/L; the bacterial inoculation concentration to enzymatically hydrolyzed solution, 6%; fermentation temperature, 37 oC, the amounts of the added nutritional elements, i.e. yeast extract, CH3COONH4, KH2PO4, and C6H6N2O, 0.8, 6.0, 0.5, and 0.25 g/L, respectively. Under these conditions, the butanol yield reached 9.88 g/L. Based on the butanol metabolism pathways, supplementation of a small amount of C6H6N2O was found to effectively increase the yield of butanol production.